Deng Hanlin, Li Weihua, Qiu Feng, Shi An-Chang
State Key Laboratory of Molecular Engineering of Polymers, Key Laboratory of Computational Physical Sciences, Department of Macromolecular Science, Fudan University , Shanghai 200433, China.
Department of Physics and Astronomy, McMaster University , Hamilton, Ontario, Canada L8S 4M1.
J Phys Chem B. 2017 May 4;121(17):4642-4649. doi: 10.1021/acs.jpcb.7b01987. Epub 2017 Apr 20.
Monolayers of linear and miktoarm star ABC triblock copolymers with equal A and C blocks were investigated using self-consistent field theory. Monolayers of ABC triblock copolymers were formed between two parallel surfaces that were attractive to the A and C blocks. The repulsive interaction parameter χN between the A and C blocks was chosen to be weaker than the A/B and B/C interactions, quantified by χN and χN, respectively, such that the B blocks were confined at the A/C interface, resulting in various B domains with different geometries and arrangements. It was observed that two variables, namely, the strength of the surface fields and the film thickness, were dominant factors controlling the self-assembly of the B blocks into various morphologies. For the linear triblock copolymers, the morphologies of the B domains included disks, stripes (parallel cylinders), and hexagonal networks (inverse disks). For the miktoarm star triblock copolymers, the competition between the tendency to align the junction points along a straight line and the constraint on their arrangement from the surface interactions led to richer ordered morphologies. As a result of the packing of the junction points of the ABC miktoarm star copolymers, a counterintuitive phase sequence from low-curvature phases to high-curvature phases with increasing length of B block was predicted. The study indicates that the self-assembly of monolayers of ABC triblock copolymers provides an interesting platform for engineering novel morphologies.
使用自洽场理论研究了具有相等A和C嵌段的线性和米克托臂星形ABC三嵌段共聚物的单分子层。ABC三嵌段共聚物的单分子层形成于对A和C嵌段具有吸引力的两个平行表面之间。A和C嵌段之间的排斥相互作用参数χN被选择为比A/B和B/C相互作用弱，分别由χN和χN量化，使得B嵌段被限制在A/C界面处，从而产生具有不同几何形状和排列的各种B域。观察到两个变量，即表面场的强度和膜厚度，是控制B嵌段自组装成各种形态的主要因素。对于线性三嵌段共聚物，B域的形态包括圆盘、条纹（平行圆柱体）和六边形网络（反圆盘）。对于米克托臂星形三嵌段共聚物，连接点沿直线排列的趋势与表面相互作用对其排列的限制之间的竞争导致了更丰富的有序形态。由于ABC米克托臂星形共聚物连接点的堆积作用，预测了随着B嵌段长度增加，会出现从低曲率相到高曲率相的反直觉相序列。该研究表明，ABC三嵌段共聚物单分子层的自组装为构建新型形态提供了一个有趣的平台。
